1 Using vibration patterns to provide impact position information in haptic manipulation of virtual objects 13/06/2008 Jean Sreng Anatole Lécuyer Claude.

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Using vibration patterns to provide impact position information in haptic manipulation of virtual objects

13/06/2008

Jean SrengAnatole LécuyerClaude Andriotjean.sreng@inria.fr

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Outline

• Introduction

• Vibration patterns

• Evaluation

• Conclusion

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Introduction

• The impact between “rigid” objects :• A low-frequency reaction force of contact (simplified model)• A high-frequency force transient (more complex model)

• This high-frequency force transient can be used in haptic rendering of impact (open-loop haptic) :

• Improve the realism• Convey some information about the object’s material

• Is-it possible to convey position information using this transient ?

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Vibrations and impact position

• Chosen approach : • The impact generates vibrations depending on the impact position

• Vibration model, a first approximation• Euler-Bernouilli cantilever beam

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Vibrations and impact position

• General solution :

Impact position

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Simplified vibration patterns

• Simplified patterns based on the physical behavior• Simplified computation• Maybe easier perception ?

• Chosen model : exponentially damped sinusoid• Amplitude changes with impact position• Frequency changes with impact position• Both amplitude and frequency changes

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Simplified vibration patterns

Am

Fr

AmFr (Consistent)

AmCFr (Conflicting)

Near impact Far impact

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Evaluation

• Preliminary evaluation :• Quantitative : “Between these two impacts which one was the closest

one from the hand ?”• Qualitative : Subjective rating of the impact realism

• Conducted on 15 subjects

• Apparatus :• Virtuose6D device• Sound blocking noise headphones

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Quantitative evaluation

• Quantitative evaluation : “Between these two impacts which one was the closest one from the hand ?”

• 6 models– 2 realistic models (Euler-Bernoulli) (EB1, EB2)– 4 simplified models (Am, Fr, AmFr, AmCFr)

• 4 locations• 8 random repetitions• Total of 576 trials (40 min)

ERRATUM Page 7 § 4.3EB1: 10Hz, 64HzEB2: 5Hz, 25HzOther: 15Hz to 45Hz

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Quantitative evaluation : results

• The ratio of “good answers” was evaluated : “How well the user was able to associate a vibration and an impact location ?”

0.5 0.750.25No association

Inverted association

association

• The value was used to represent the overall performance

0 0.25 0.5

association

No association

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Quantitative evaluation : results

• Overall performance :• ANOVA Significant (p < 0.007)• Paired t-tests (p < 0.05) :

– Am -– EB1– EB2– AmCFr

– Fr -– EB1– EB2

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Quantitative evaluation : results

• Inversion ratio : The ratio of users who inverted the association between the vibration pattern and the position

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Qualitative evaluation : results

• Rate the impact realism :• Paired t-tests :

– Am– EB1– EB2– Fr– AmFr

– EB2– Fr– AmCFr

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Discussion

• Global weak inter – subject correlation : • Each subject seems to have his/her own interpretation (inversion or not)

• Strong intra – subject consistency :• Subjects seem to be very consistent within his/her interpretation

• Several strong inter – subject correlation between models :• Fr and AmCFr strongly correlated

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Conclusion

• We proposed several vibration patterns to convey impact position information

• We conducted a preliminary evaluation :• The user is able to use the vibration pattern to get an impact position

information• The simplified models Am and Fr seems to perform better

• Future work :• Evaluate the role of the hand impedance and the haptic device

bandwidth to elaborated more effective feedback• Deeper analysis of the data• New models

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Questions ? ?